The present invention relates to the preparation of activated carbon and specifically pertains to a preparation method for asphalt-based spherical activated carbon which requires no infusibilization process.
Asphalt-based spherical activated carbon has many advantages which include good sphericity, high mechanical strength, fixed bed capacity with low resistance, strong wide-spectrum adsorption, high absorption and desorption rate and regenerability. It is widely used in environmental protection, medical, chemical and military fields. It is a high-end variety in the family of activated carbon, but its high technical cost is a major obstacle to industrial production, promotion and application.
The present production of asphalt-based spherical activated carbon, as represented by Kureha Chemical Industry Co., Ltd. of Japan, must go through five steps: 1. preparing modified asphalt raw materials; 2. shaping asphalt particles into spheres; 3. undergoing infusibilization process (including chemical impregnation); 4. carbonizing asphalt spherical particles; 5. activating asphalt spherical carbon. To prevent the spherical particles from melting during high-temperature carbonization, the asphalt spherical particles must undergo infusibilization before carbonization. This is called the infusibilization process in the industry.
The existing asphalt-based spherical activated carbon treatment process is highly related to the fact that the spherical particles are in the molten state during the shaping process. No matter the shaping process is done by suspension, emulsification, pyrocondensation polymerization or other methods, asphalt particles automatically shrink into spheres in a non-mutually exclusive liquid phase (or gas phase) medium by means of their own surface tension when they are in the molten state. The spherical asphalt particles prepared by such process must undergo the infusibilization process before entering the high-temperature carbonization stage.
The infusibilization process is the most difficult technical aspect of the entire process and because of this its processing cost is often more than half of the total cost. The infusibilization process raises technical difficulty of processing asphalt-based spherical activated carbon sharply, thereby significantly increasing the cost of production.